Enhancing the Efficiency of Geotechnical Piling Operations: A Comparative Analysis of Polymer and Bentonite Slurries

Abstract

Deep foundation engineering relies on stabilizing fluids to ensure borehole integrity during the construction of cast-in-situ piles, particularly in unstable soil conditions. For over six decades, bentonite slurry has been the industry-standard stabilizing agent. However, its application is increasingly constrained by significant operational inefficiencies, high logistical costs, and adverse environmental impacts, including the generation of large volumes of contaminated waste. This paper presents a detailed, field-based comparative analysis of synthetic polymer-based fluids as a high-efficiency alternative to traditional bentonite slurry in bored piling operations. The study was conducted on the Mumbai–Ahmedabad High Speed Rail (MAHSR) project, providing a direct comparison of the two methods under identical geotechnical conditions for 1.5-meter diameter, 55-meter deep piles. Key performance indicators—including project duration, direct and indirect costs, manpower deployment, fuel consumption, muck disposal logistics, and overall productivity—were systematically quantified. The outcome demonstrate that the adoption of polymer slurry leads to a profound enhancement in operational efficiency, doubling the daily output from one to two piles cast per day. A granular cost analysis of 20 pile borings reveals a net cost saving of 46.7%, driven by substantial reductions in fuel (44.1%), manpower (40.7%), and muck disposal (85.3%). Beyond economic benefits, polymer fluids offer superior environmental performance due to their biodegradability and the elimination of complex slurry disposal protocols. This research provides conclusive, data-driven evidence that replacing bentonite with advanced polymer fluids is a strategically sound decision that significantly improves the technical, economic, and environmental sustainability of modern piling works.

Introduction

Bentonite slurry has been used for over 60 years to stabilize deep excavations during pile and diaphragm wall construction. It prevents borehole collapse and forms a protective "filter cake." However, bentonite has operational drawbacks, including:

• Long hydration time (up to 24 hours)

• Sensitivity to water quality

• High labor and fuel requirements

• Difficult waste management and disposal

To address these issues, synthetic polymer fluids have emerged as an efficient alternative. These fluids:

• Require no hydration period

• Are effective in a wide range of soil/water conditions

• Form a thin, impermeable membrane (not a filter cake)

• Are biodegradable and easier to dispose of

2. Objectives of the Study

This study aimed to quantitatively compare bentonite and polymer slurry systems across:

• Construction cycle time

• Total project cost

• Manpower and fuel usage

• Muck disposal volume and cost

• Site productivity

3. Methodology

• Conducted on the Mumbai–Ahmedabad High-Speed Rail (MAHSR) project in India.

• 40 piles (20 with bentonite, 20 with polymer) of 1.5m diameter and 55m depth were analyzed.

• Measured key metrics: cost, fuel, labor, disposal, and pile construction speed.

4. Key Findings

? Cost Savings

????‍?? Labor and Fuel Use

• Manpower for slurry prep: Reduced by ~70% (25 workers → 7)

• Fuel cost per 20 piles: ?25.58 lakh (bentonite) vs. ?14.30 lakh (polymer)

?? Muck Disposal

• Bentonite slurry creates contaminated waste (difficult to handle and transport)

• Polymer slurry results in drier, reusable muck

• 85.3% reduction in disposal costs

???? Productivity Gains

• Bentonite: 1 pile/day

• Polymer: 2 piles/day

• 50% reduction in cycle time, enabling faster project delivery

5. Discussion

• Polymer slurry offers a transformative improvement, not just an incremental one.

• Cost, time, labor, and environmental performance all favor polymers.

• Sustainability: Biodegradable, less waste, lower environmental footprint.

• Higher material cost of polymers is offset by holistic project savings.

• Clean interface and better soil-concrete bond improve foundation quality.

Conclusion

This comprehensive, field-based comparative study confirms that the replacement of traditional bentonite slurry with modern polymer-based fluids yields significant improvements in the efficiency, cost-effectiveness, and sustainability of bored piling operations. The key conclusions are as follows: 1) Economic Viability: The use of polymer slurry delivered a total project cost saving of 46.7%. This was not due to a single factor but a systemic improvement, with major contributions from reduced muck disposal costs (85.3% savings), fuel consumption (44.1% savings), and manpower (40.7% savings). 2) Productivity Gains: The operational efficiencies inherent in the polymer system—including instant mixing, faster cleaning, and simplified logistics—resulted in a 100% increase in productivity, doubling the daily output of completed piles. 3) Resource Optimization: The polymer method significantly reduces the demand for labor and the consumption of non-renewable resources like fuel, leading to a more streamlined and efficient allocation of project resources. 4) Environmental Sustainability: The polymer system is an environmentally superior alternative. Its biodegradability and the drastic reduction in contaminated waste align with modern green construction principles and mitigate regulatory and disposal risks. Based on these conclusive findings, the adoption of polymer-based fluids is strongly recommended for large-scale piling projects. The initial investment in polymer material is more than justified by the substantial and multifaceted returns in terms of cost, time, and environmental performance. Future research should focus on the long-term performance and durability of piles cast with polymer slurry and explore the potential of next-generation bio-polymers to further advance the sustainability of deep foundation construction.

References

[1] Jefferis, S.A. and Lam, C., 2013, September. Polymer support fluids: use and misuse of innovative fluids in geotechnical works. In 18th International Conference on Soil Mechanics and Geotechnical Engineering (pp. 3219-3222). Presses des Ponts. 8 [2] Lam, C. and Jefferis, S.A., 2018. Polymer support fluids in civil engineering. London: Ice Publishing. 13 [3] Hasan, H.N. and Al-Saidi, A.A.A., 2024, January. Effect of polymer and bentonite on the performance of bored pile: A review. In AIP Conference Proceedings (Vol. 2864, No. 1, p. 030008). AIP Publishing LLC. 12 [4] Larisch, M.D., 2022, February. Construction and stability risks for fluid supported deep excavations and their effects on design parameters. In Proceedings of the DFI-PFSF Piling & Ground Improvement Conference, Sydney, Australia (pp. 23-25). 11 [5] Carico, R.D. and Bagshaw, F.R., 1978, October. Description and use of polymers used in drilling, workovers, and completions. In SPE Production Technology Symposium (pp. SPE-7747). SPE. 10 [6] Tripathi, V., 2025. Enhancing the Overall Efficiency of Piling Work by Using Polymer in Place of Bentonite Slurry. Master\'s Thesis, Panjab University, Chandigarh, India. 7

Copyright

Copyright © 2025 Vineet Tripathi, Ajay K. Duggal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.